Apparatus and process for adding solids to a liquid



Sept. 13, 1966 v. D. SWEENEY ETAL 3,

APPARATUS AND PROCESS FOR ADDING SOLIDS TO A LIQUID Filed July 23, 1963 2 Sheets-Sheet 1 [Pas I NVENTORS WALTER u. KAJI BY VICTOR D. SWEENEY A TORNEYS Sept. 13, 1966 v. D. SWEENEY ETAL 3,

APPARATUS AND PROCESS FOR ADDING SOLIDS TO A LIQUID Filed July 25, 1963 2 Sheets-Sheet 3 f l ggl I II T' "T l Fig. 3

INVENTORS WALTER U. KAJI BY VIC/T21 D. SWEEQIEY ATTORNEYS United States Patent 3,272,6l9 APPARATUS AND PROQESS FOR ADDING SOLIDS TO A LIQUID Victor D. Sweeney, Euclid, and Walter U. Kaji, Chagrin Falls, Ohio, assignors to Metal Pumping Services, Inc., Cleveland, Ohio, a corporation of Ohio Filed fully 23, 1963, Ser. No. 297,076

16 Claims. (Cl. 75-65) This invention relates to a process and apparatus for dissolving solids in a liquid and, more particularly, to the smelting of light metals for the purpose of refining, purifying, modifying, and mixing them.

In the production of useful shapes from light metals, such as, for example, aluminum, it is necessary to reduce the metal to a liquid state in order to refine, purify, alloy, and/or mix the base metal. It is customary in the art of smelting light metals to maintain a bath of molten metal and submerge solid metals into the melt to effect a rapid heat transfer from the molten metal to the solid metal so that the solid metal is reduced to a liquid state. Large pieces of metal to be thus smelted are handled without undue difficulty since theysink rapidly in the melt. Small metal particles, such as cuttings, turnings, filings, and chips, are difiicult to immerse, however, not only because of the small, lightweight, and buoyant character of the particles or pieces, but because the surface of the molten bath may be covered with an oxide or slag layer. This layer acts as a support for the small particles and resists their introduction or movement into the bath of molten metal underneath. Hence, small particles of light metal, when placed on the top of a smelting bath, tend to be exposed for an excessive length of time to the oxidizing atmosphere of the air and the contaminating impurities in the slag layer, while at the same time being subjected to the heat of the slag and the molten body of metal underneath. Frequently, these particles do not enter the melt at all as a metal but merely form more slag by being oxidized.

Skimming the slag at intervals in order to introduce these particles into the melt is not sound melting practice since the oxide layer which covers the melt offers considerable protection against gas absorption. Frequent disturbance of the surface oxide not only permits more oxide to be formed and permits the deleterious absorption of gases into the melt, but also tends to trap oxide particles in the melt which constitute nonmetallic inclusions in the castings. If the melt is allowed to stand for a considerable period of time, the oxide particles rise to the surface.

The trapping of oxide particles is not an important problem in the case of the heavier metals, such as iron. nickel, and cobalt, since the difference in specific gravity between the metal and its oxide permits a rapid separation. Light metals, such as aluminum, and their oxides, have specific gravities that are so close that separation by gravity requires a long period of time. Long soaking periods, however, even though beneficial from the standpoint of cleanliness, permit deleterious gases to be dissolved in the melt.

For all of these reasons, good melting procedure for light metals involves the maintenance of a quiet melt and the careful manipulation of the melt during the addition of solid metals and fluxes and during mixing operations. A particularly successful means for smelting light metals such as aluminum is set forth in the patent to Bonsack et al. Patent No. 2,528,208, granted Oct. 31, 1950. This patent sets forth a smelting process in which a stream of molten metal is continuously withdrawn from a relatively large body of molten metal and is poured or directed over, through or into solid metal pieces, so as to rapidly immerse, surround, or engulf the solid metal and, through intimate contact therewith, effect a rapid heat transfer between the melt and the solid metal.

While this patented process is successful in many instances, the speed at which the particles are immersed is, to a great degree, dependent upon the size and condition of the particles and the rate of flow of the molten metal over the particles. The rate of flow cannot be too high, however, since splashing and severe oxidation will result. The resulting relatively constant rate of immersion produced by the process was often too slow for extremely fine particles and too rapid for contaminated particles, such as, for example, oil soaked cuttings and turnings. These contaminated particles should remain on or in the slag layer so that the contaminants may be burned off and then quickly immersed prior to oxidation. Since this was impossible according to many prior art practices, these contaminated particles were pre-heated in an oven to drive ofii the contaminants and were then introduced into the melt.

It is, therefore, a general object of this invention to provide a method and apparatus that overcomes many of the foregoing problems of the prior art.

It is a more specific object of this invention to provide a method and apparatus for smelting metal, particularly light metal such as aluminum, wherein a stream of molten metal is continuously withdrawn from a body of molten metal and poured or directed at a relatively constant rate along a curved path to form a vortex or whirlpool into which solid metal particles are introduced and in which the intensity of the vortex is controlled to immerse the solid metal in the molten metal at any desired rate.

It is a further object of this invention to perform the above operations with a minimum amount of splashing and oxidation of the melt.

It is a further object of this invention to provide a method and apparatus for smelting metal wherein contaminated solid metal particles may be introduced into the bath by maintaining the contaminated particles on or in the slag layer until the contaminants have been burned off and then quickly immersed in the bath prior to oxidation of the particles.

It is another object of this invention to provide a method and apparatus for introducing solid fluxes into a molten metal bath at a controlled rate.

In general, the foregoing objects are achieved by maintaining a liquid bath, confining a portion of the surface and a portion of the liquid below the surface in a laterally restricted zone, withdrawing liquid from below the surface of the bath at a location outside of the restricted zone and forcibly conducting the liquid so withdrawn into the restricted zone and along a curved path in the zone to create a vortex in the restricted zone and in a position of the bath below the restricted zone. Particulate solids are fed into the vortex and are submerged in the liquid bath at any desired rate by varying the intensity of the vortex.

These and other objects and advantages of the invention will become apparent from the following description and accompanying drawings.

In the drawings:

FIGURE 1 is an elevational view, partly diagrammatic and partly in section, of a furnace and metal handling device embodying the present invention and suitable for use in carrying out the process contemplated herein.

FIGURE 2 is a fragmentary plan view of the device illustrated in FIGURE 1.

FIGURE 3 is an elevational view of an alternate molten metal hopper arrangement suitable for use with the device shown in FIGURE 1.

FIGURE 4- is a top plan view of the hopper shown in FIGURE 3.

Referring now to the drawings and particularly to FIGURES 1 and 2, the apparatus of the present invention includes a furnace for holding and heating a mass of molten metal. The furnace 10 is preferably of the reverberatory type, although other heaters may be employed. A suitable outlet opening (not shown) is provided in a sidewall of the furnace adjacent the level of the heart-h. This outlet opening is plugged during the smelting process and when the smelting is complete, the plug is withdrawn so that the molten metal flows to ladles, ingot molds and the like, for subsequent use as desired.

An open auxiliary hearth 11 is provided on the outside of the furnace 10 along a front wall 12. The auxiliary hearth 11 may be on the same level as the main hearth (not shown) in the furnace 10. The hearth 111 is enclosed by upright refractory lined side walls 13, thus providing an open-topped receptacle disposed on the outside of the enclosed chamber of the furnace 10 and separated therefrom by the front wall 12.

At one end of the auxiliary hearth 11 an opening or passage 14 is formed through the front wall 12 adjacent the bottom thereof. The auxiliary hearth 11 thus communicates with the hearth of the furnace 10 through the passage 14, permitting the flow of molten metal from one hearth to the other, thereby maintaining substantially equal levels of molten metal on the two hearths. The passage 14 is provided below the level of the molten metal in the two hearths to prevent the atmosphere from being admitted into the furnace 10. The circulation of molten metal as contemplated by this invention involves a flow from a relatively large body of metal in the furnace 10 through the low, relatively small passage or opening .14 onto the auxiliary hearth and return to the furnace hearth through a relatively larger passage or opening 15 formed through the front wall 12 at the other end of the auxiliary hearth 11. A slidable or vertically movable closure or .door 16 of refractory material is provided for the passage 15. Normally, the closure 16 is adjusted to or just below the surface of the metal in the open auxiliary hearth compartment. The gate or closure 16 thus prevents the flow of slag or dross on the surface of the auxiliary hearth metal into the chamber of the main furnace 10 and seals the main chamber and its bath of molten metal from the outside atmosphere, keeping the heat in and the air out.

A cross wall or partition 17 of fire brick or similar material divides the body of metal on the auxiliary hearth 11 into a feed portion A and a refining portion B. The precise levels of the metal portions A and B shown in the drawings are purely arbitrary since the levels will rise and fall slightly relative to one another, depending upon the viscosity of the metal and other factors. During the building up of a batch of metal in the furnace from the original heel or relatively shallow bat-h of molten metal, the general level of the metal will progressively rise.

The level of the feed portion A of metal is maintained by gravity substantially equal to that of the molten metal on the main hearth inside the heating portion of the furnace 10 by flow through the opening 14.

The position of the partition 17 is such that the refining portion B of the auxiliary hearth III is several times larger than the feed portion A, the latter serving merely to supply a pump 18 which is suspended in the portion A.

The pump 18, which may be of the type disclosed in the patent to Sweeney et al., Patent No. 3,048,384, granted Aug. 7, 1962, is mounted on an end portion 19 of a supporting frame 20. This pump 18, comprising an upright body 21 containing the vertical shaft, impeller, chambers, and passages of the pump, and an actuating motor 22, has a bottom inlet 23 through which metal is drawn from the feed portion A and has an outlet 24 above the level of the partition 17 through which the molten metal is discharged.

A funnel or hopper 25 is removably mounted on an .opposite end portion 26 of the frame between opposed gripping plates 27. A conduit 28 is connected to the pump outlet 24 and directs a stream S of molten metal against an inner side wall 29 of the hopper 25. The stream should strike the side wall 29 substantially tangentially and be guided by the side wall 29 in a laminar flow pattern downwardly and inwardly to an outlet opening 30 in the generally flat bottom of the hopper 25. This flow pattern forms a whirlpool or vortex in the hopper and in a portion of the bath below the hopper.

The particular curvature of the side wall 29 is not critical as long as this curvature provides the above-described iaminar flow pattern from a relatively wide inlet opening, e.g., the open top mouth of the hopper 25, to a relatively small outlet opening, e.g., the outlet opening 30. To provide this flow, horizontal cross sections of the side wall 29 are preferably substantially circular with decreasing diameters as the opening is approached.

The frame 20 is suspended by a hook 31 so that the opening 30 of the hopper 25 is submerged a predetermined depth below the level L of the metal in the portion B. The pump 18 is constructed and mounted on the frame 20 so that its bottom opening 23 is always below the level of the opening 30 and below the level L of the molten metal in the portion A.

The hook 31 supports the frame 20 in vertical alignment with the center of gravity of the frame 20, the pump 18, and the hopper 25 so that the resulting force of the system acts generally along the axis of a suspending bar 32 which is fixed to the frame and is suspended from the hook 31. The hook 31 and the structure comprising the frame 20, the pump 18, and the hopper 25 are attached to a vertically movable linkage 33 for submerging a lower portion of the hopper 25 and, therefore, the inlet opening 23 of the pump 18 a predetermined distance below the levels L and LL, respectively, of the molten metal. The submerged lower portion of the hopper 25 confines a portion of the surface and a portion of the molten metal below the surface in a laterally restricted zone. The amount of molten metal confined in this zone may be varied by raising and lowering the hopper 25 relative to the level L. The linkage 33 may be for example, a chain that is raised or lowered by a sprocket 34 and a reversing motor 35, schematically illustrated in FIGURE 1. The motor 35 may be operated manually or by being slaved to a hot metal probe (not shown), or both. The probe may be attached to the outer wall of the hopper 25 to extend downwardly and be in contact with the surface of the molten metal in the portion B when the level L fluctuates to keep the hopper 25 submerged to a predetermined depth. The linkage 33 may also be a chain that is attached to a conventional chain hoist or crane.

The particular depth to which the hopper is submerged in the portion B and, therefore, the amount of molten metal confined in the laterally restricted zone determines the intensity of the whirlpool or vortex created by the stream S acting on the side wall 29 of the hopper 25. The intensity of the vortex is an inverse function of the depth of submergence of the hopper 25. In the position illustrated in FIGURE 1, the vortex is relatively intense, and this type vortex is suitable for quickly submerging clean, solid, metal particles and solid fluxes by introducing these solids directly into the vortex. The hopper 25 may be submerged to the position illustrated in phantom outline in FIGURE 1 to create a relatively passive vortex. This type vortex is suitable for the introduction of oilcontaminated particles. The contamined particles remain on the surface of the passive vortex so that the oil is driven off by the heat of the bath. After the oil is driven off, the hopper 25 is raised to the position illustrated in solid outline in FIGURE 1 to quickly immerse the particles prior to their oxidation, thus minimizing the introduction of contaminants and/or oxides into the bath.

Referring now to FIGURES 3 and 4, a hopper 25a is illustrated. The hopper 25a may be inserted in the frame Ed in the same manner as the hopper 25. The hopper 25a has an inner side wall 2% that slopes downwardly and inwardly to an outlet opening 30a. This sloping surface provides a more intense vortex or whirlpool than the hopper 25 at comparable levels in the portion B.

A conduit 28a is connected at one end to the pump outlet 24, in place of the conduit 28, and is connected at its other end to the hopper 25a. The conduit 28:: extends through the side wall of the hopper 25a at a point that is adjacent to the outlet opening 3% so that the point of entry of the molten metal into the hopper is below the level of the bath. The conduit 28a enters the hopper 25a substantially tangentially to create a vortex. Since the molten metal is fed into the hopper at an entry point that is below the level of the molten metal in the portion B, splashing and oxidation of the metal are minimized.

Obviously, many modifications and variations of the invention will become apparent to those skilled in the art in the light of the above teachings. Therefore, it is to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically shown and described.

What is claimed is:

1. Apparatus for dissolving a solid in a liquid, comprising receptacle means for maintaining a liquid bath, means for confining a portion of the top surface of the liquid bath and a portion of the vertical extent of the liquid below the surface in a laterally restricted zone, means for withdrawing liquid from below the surface of the bath at a location outside of said restricted zone and forcibly conducting the liquid so withdrawn into said restricted zone, means for guiding said liquid along a curved path in said restricted zone to create a vortex in the restricted zone and in a portion of the bath below the zone, means for varying the vertical distance between said receptacle means and said confining means to thereby alternately increase and decrease the amount of liquid confined in the zone and to thereby vary the intensity of the vortex and submerge solids introduced into said vortex at any desired rate.

2. Apparatus for dissolving particulate solids in molten metal, comprising receptacle means for maintaining a bath of molten metal, means for confining a portion of the top surface of the molten metal bath and a portion of the vertical extent of the molten metal below the surface in a laterally restricted zone, means for withdrawing molten metal from below the surface of the bath at a location outside of said restricted zone and forcibly conducting the molten metal so withdrawn into said restricted zone, means for guiding the molten metal along a curved path in said zone to create a vortex in the restricted zone and in a portion of the bath below the zone, means for varying the vertical distance between said receptacle means and said confining means to thereby alternately increase and decrease the amount of molten metal confined in the zone and to thereby vary the intensity of the vortex and submerge solids introduced into said vortex at any desired rate.

3. Apparatus for dissolving a solid in a liquid comprising an open-topped receptacle for maintaining a liquid bath, a wall dividing said receptacle into first and second portions, means providing fiuid communication between said portions and below the level of the liquid contained therein, a pump in said first portion having an inlet opening below the level of the bath in the first portion and an outlet opening above the level of the bath, a hopper in said second portion having a relatively small outlet opening in a bottom of the hopper below the level of the liquid in said second portion to confine a predetermined amount of liquid in said hopper, said hopper having a relatively large top opening and a curved side wall sloping inwardly from said top opening to said hopper outlet opening, a conduit connected to the outlet opening of said pump and extending into said hopper so as to direct a stream of liquid tangentially against the side wall of said hopper to thereby create a vortex in the liquid confined in said hopper and in a portion of the bath below the outlet opening of the hopper, means for raising and lowering the hopper relative to the surface of the bath in said second portion and relative to said second portion to thereby alternately increase and decrease the amount of liquid confined in said hopper, to vary the intensity of the vortex, and to submerge solids introduced into said vortex at any desired rate.

4. Apparatus for dissolving particulate solids in molten metal, comprising a furnace having a hearth for holding a body of molten metal, an open-topped receptacle fixed to a wall of said furnace for holding a bath of molten metal, a wall dividing said receptacle into first and second portion, openings in said furnace wall below the level of molten metal in said first and second portions to establish fluid communication between said furnace and said first and second portions, a frame suspended over said receptacle, a pump fixed to one end of said frame and having an inlet opening below the level of the molten metal in said first portion, said pump having an outlet opening above the level of the bath, a hopper fixed to the other end of said frame and having a relatively small outlet opening in a bottom of the hopper below the level of the molten metal in said second portion to confine a predetermined amount of metal in said hopper, said hopper having a relatively large top opening and a curved side wall sloping inwardly from said top opening to said hopper outlet opening, a conduit connected to the outlet opening of said pump and extending tangentially into said hopper to direct a stream of molten metal against the side wall of said hopper and thereby create a vortex in the liquid confined in said hopper and in a portion of the bath below the outlet opening of the hopper, means for raising and lowering the frame to thereby raise and lower the hopper relative to the surface of the bath in the second portion and relative to said second portion, to alternately increase and decrease the amount of molten metal confined in the hopper, to thereby vary the intensity of the vortex, and to submerge solids introduced into said vortex at any desired rate.

5. Apparatus for dissolving a solid in a liquid comprising an open-topped receptacle for maintaining a liquid bath, a wall dividing said receptacle into first and second portions, means providing fluid communication between said portions and below the level of the liquid contained therein, a pump in said first portion having an inlet opening below the level of the bath in the first portion and an outlet opening above the level of the bath, a hopper in said second portion having a relatively small outlet opening in a bottom of the hopper below the level of the liquid in said second portion to confine a predetermined amount of liquid in said hopper, said hopper having a relatively large top opening and a curved side wall sloping inwardly from said top opening to said hopper outlet opening, a conduit connected to the outlet opening of said pump and extending tangentially into said hopper, through the side wall of the hopper, and below the level of the liquid in the second portion so as to direct a stream of molten metal tangentially into the liquid confined in said hopper and to thereby create a vortex in the contfined liquid and in a portion of the bath below the outlet opening of the hopper, means for raising and lowering the hopper relative to the surface of the bath in said second portion and relative to said second portion to thereby alternately increase and decrease the amount of liquid confined in said hopper, to vary the intensity of the vortex, and to submerge solids introduced into said vortex at anv desired rate.

6. Apparatus for dissolving particulate solids in molten metal, comprising a furnace having a hearth for holding a body of molten metal, an open-topped receptacle fixed to a wall of said furnace, a wall dividing said receptacle into first and second portions, openings in said furnace wall below the level of molten metal in said first and secend portions to establish fluid communication between said furnace and said first and second portions, a frame suspended over said receptacle, a pump fixed to one end of said frame and having an inlet opening below the level of the molten metal in said first portion, said pump having an outlet opening above the level of the bath, a hopper fixed to the other end of said frame and having a relatively small outlet opening in a bottom of the hopper below the level of the molten metal in said second portion to confine a predetermined amount of metal in said hopper, said hopper having a relatively large top opening and a curved side wall sloping inwardly from said top opening to said hopper outlet opening, a conduit connected to the outlet opening of said pump and extending tangentially into said hopper, through the side wall of the hopper, and below the level of the molten metal in the second portion so as to direct a stream of molten metal tangentially into the molten metal confined in said hopper and to thereby create a vortex in the confined molten metal and in a portion of the bath below the outlet opening of the hopper, means for raising and lowering the frame to thereby raise and lower the hopper relative to the surface of the bath in the second portion and relative to said second portion, to alternately increase and decrease the amount of molten metal confined in the hopper, to vary the intensity of the vortex, and to submerge solids introduced in said vortex at any desired rate,

7. A device for dissolving particulate solids in molten metal, comprising means for confining a body of molten metal, a frame having spaced end portions, a pump fixed to one end portion of said frame, said pump having an inlet opening at its bottom and an outlet opening at its top, a hopper fixed to the other end portion of said frame and having a relatively small outlet opening in a bottom of the hopper, said hopper having a relatively large top opening and a curved side wall sloping inwardly from said top opening to the bottom of the hopper, a conduit connected to the outlet opening of said pump and extending into said hopper, and means for suspending said frame over said confining means so that said pump and said hopper extend into the body of molten metal.

8. A device for dissolving particulate solids in molten metal, comprising means for confining a body of molten metal, a frame having spaced end portions, a pump fixed to one end portion of said frame, said pump having an inlet opening at its bottom and an outlet opening at its top, a hopper fixed to the other end portion of said frame and having a relatively small outlet opening in a bottom of the hopper, said hopper having a relatively large top opening and a curved side wall sloping inwardly from said top opening to the bottom of the hopper, a conduit connected to the outlet opening of said pump and extend.- ing into said hopper, and means for suspending said frame over said confining means and for raising and lowering the frame relative to said confining means.

9. A device for dissolving particulate solids in molten metal, comprising means for confining a body of molten metal, a frame having spaced end portions, a pump fixed to one end portion of said frame, said pump having an inlet opening at its bottom and an outlet opening at its top, a hopper fixed to the other end portion of said frame and having a relatively small outlet opening in a bottom of the hopper, said hopper having a relatively large top opening and a curved side wall sloping inwardly from said top opening to said bottom opening, a conduit connected to the outlet opening of said pump and extending into said hopper through the side wall of the hopper, and means for suspending said frame over said confining means so that said pump and said hopper extend into the body of molten'metal.

10. A device for dissolving particulate solids in molten metal, comprising means for confining a body of molten metal, a frame having spaced end portions, a pump fixed to one end portion of said frame, said pump having an inlet opening at its bottom and an outlet opening at its top, a hopper fixed to the other end portion of said frame and having a relatively small outlet opening in a bottom of the hopper, said hopper having a relatively large top opening and a curved side wall sloping inwardly from said top opening to said bottom opening, a conduit connected to the outlet opening of said pump and extending into said hopper through the side wall of the hopper, and means for suspending said frame over said confining means and for raising and lowering the frame relative to said confining means.

11. A process of dissolving a solid in a liquid, comprising the steps of maintaining a liquid bath, confining a portion of the upper surface and a portion of the vertical extent of the liquid below said surface of the bath in a laterally restricted zone, withdrawing liquid from below said surface of the bath at a location outside of said restricted zone and forcibly conducting the liquid so withdrawn into said restricted zone at a substantially constant rate and along a curved path in said zone to create a vortex in the restricted zone and in a portion of the bath below the zone, feeding particulate solids into said vortex and varying the intensity of said vortex by alternately increasing and decreasing the amount of liquid confined in the zone to submerge and dissolve the particulate solids at any desired rate while continuing to introduce liquid into said zone at said substantially constant rate, the rate of submergence being an inverse function of the amount of liquid confined in the restricted zone.

12. A process of dissolving particulate solids in molten metal, comprising the steps of maintaining a bath of molten metal, confining a portion of the upper surface and a portion of the vertical extent of the molten metal below said surface of the bath in a laterally restricted zone, withdrawing molten metal from below said surface of the bath at a location outside of said restricted zone and forcibly conducting the metal so withdrawn into said restricted zone at a substantially constant rate and along a curved path in said zone to create a vortex in the restricted zone and in a portion of the bath below the zone, feeding particulate solids into said vortex and varying the intensity of said vortex by alternately increasing and decreasing the amount of metal confined in the zone to submerge and dissolve said solid-s at any desired rate while continuing to introduce molten metal into said zone at said substantially constant rate, the rate of submergence being an inverse function of the amount of metal laterally confined in the restricted zone.

13. A process of smelting metals comprising the steps of maintaining a bath of molten metal, confining a portion of the upper surface and a portion of the vertical extent of the molten metal below said surface of the bath in a laterally restricted zone, withdrawing molten metal from below said surface of the bath at a location outside of said restricted zone and forcibly conducting the metal so withdrawn into said restricted zone at a substantially constant rate and along a curved path in said zone to create a vortex in the restricted zone and in a portion of the bath below the zone, feeding particulate metal into said vortex and varying the intensity of said vortex by alternately increasing and decreasing the amount of metal confined in the zone to submerge and dissolve the solid particulate metal at any desired rate while continuing to introduce molten metal into said zone at said substantially constant rate, the rate of submergence being an inverse function of the amount of metal laterally confined in the restricted zone.

14. A process of smelting metals contaminated with a substance that is capable of being volatilized, comprising the steps of maintaining a bath of molten metal, confining a portion of the upper surface and a portion of the vertical extent of the molten metal below said surface of the bath in a laterally restricted zone, withdrawing molten metal from below said surface of the bath at a location outside of said restricted zone and forcibly conducting the me al SQ withdrawn into said restricted zone at a substantially constant rate and along a curved path in said zone to create a vortex in the restricted zone and in a portion of the bath below the zone, feeding particulate metal contaminated with a substance that is capable of being volatilized into said vortex, maintaining said vortex in a relatively passive state to maintain the contaminated metal on the surface until the substance is volatilized by confining a relatively large amount of metal in said zone, and then increasing the intensity of the vortex by decreasing the amount of metal in said zone while continuing to introduce molten metal into said zone at said substantially constant rate to rapidly submerge and dissolve the solid particulate metal.

15. A process of smelting metals, comprising the steps of maintaining a bath of molten metal, confining a portion of the upper surface and a portion of the vertical extent of the molten metal below said surface of the bath in a laterally restricted zone, withdrawing molten metal from below said surface of the bath at a location outside of said restricted zone and forcibly conducting the metal so withdrawn into said restricted zone below the surface of the bath at a substantially constant rate and along a curved path in said zone to create a vortex in the restricted zone and in a portion of the bath below the zone, feeding particulate metal into said vortex and varying the intensity of said vortex by alternately increasing and decreasing the amount of metal confined in the zone to submerge and dissolve the solid particulate metal at any desired rate while continuing to introduce molten metal into said zone at said substantially constant rate, the rate of submergence being an inverse function of the amount of metal laterally confined in the restricted zone.

16. A process of smelting metals contaminated with a substance that is capable of being volatilized, comprising the steps of maintaining a bath of molten metal, confining a portion of the upper surface and a portion of the vertical extent of the molten metal below said surface of the bath in a laterally restricted zone, withdrawing molten metal from below said surface of the bath at a location outside of said restricted zone and forcibly conducting the metal so withdrawn into said restricted zone below the surface of the bath at a substantially constant rate and along a curved path in said zone to create a vortex in the restricted zone and in a portion of the bath below the zone, feeding particulate metal contaminated with a substance that is capable of being volatilized into said vortex, maintaining said vortex in a relatively passive state to maintain the contaminated metal on the surface until the substance is volatilized by confining a relatively large amount of metal in said zone, and then increasing the intensity of the vortex by decreasing the amount of metal in said zone while continuing to introduce molten metal into said zone at said substantially constant rate to rapidly submerge and dissolve the solid particulate metal.

References Cited by the Examiner UNITED STATES PATENTS 1,933,577 11/1933 Wille 266-13 2,528,208 10/1950 Bonsack -68 2,803,450 8/1957 McFeaters 266-13 OTHER REFERENCES Perry et 211.: Chemical Engineers Handbook, 3rd. ed., p. 1334 (McGraw Hill, 1950).

HYLAND BIZOT, Primary Examiner.

DAVID L. RECK, Examiner.

H. W. CUMMINGS, H. TARRING,

Assistant Examiners. 

3. APPARATUS FOR DISSOLVING A SOLID IN A LIQUID COMPRISING AN OPEN-TOPPED RECEPTACLE FOR MAINTAINING A LIQUID BATH, A WALL DIVIDING SAID RECEPTACLE INTO FIRST SECOND PORTIONS, MEANS PROVIDING FLUID COMMUNICATION BETWEEN SAID PORTIONS AND BELOW THE LEVEL OF THE LIQUID CONTAINED THEREIN, A PUMP IN SAID FIRST PORTION HAVING AN INLET OPENING BELOW THE LEVEL OF THE BATH IN THE FIRST PORTION AND AN OUTLET OPENING ABOVE THE LEVEL OF THE BATH, A HOPPER IN SAID SECOND HAVING A RELATIVELY SMALL OUTLET OPENING IN A BOTTOM OF THE HOPPER BELOW THE LEVEL OF THE LIQUID IN SAID SECOND PORTION TO CONFINE A PREDETERMINED AMOUNT OF LIQUID IN SAID HOPPER, SAID HOPPER HAVING A RELATIVELY LARGE TOP OPENING AND A CURVED SIDE WALL SLOPING INWARDLY FROM SAID TOP OPENING TO SAID HOPPER OPENING, A CONDUIT CONNECTED TO THE OUTLET OF SAID PUMP AND EXTENDING INTO SAID HOPPER SO AS TO DIRECT A STREAM OF LIQUID TANGENTIALLY AGAINST THE SIDE WALL OF SAID HOPPER TO THEREBY CREATE A VORTEX IN THE LIQUID CONFINED IN SAID HOPPER AND IN A PORTION OF THE BATH BELOW THE OUTLET OPENING OF THE HOPPER, MEANS FOR RISING AND LOWERING THE HOPPER RELATIVE TO THE SURFACE OF THE BATH IN SAID SECOND PORTION AND RELATIVE TO SAID SECOND PORTION TO THEREBY ALTERNATELY INCREASE AND DECREASE THE AMOUNT OF LIQUID CONFINED IN SAID HOPPER, TO VARY THE INTENSITY OF THE VORTEX, AND TO SUBMERGE SOLIDS INTRODUCED INTO SAID VORTEX AT ANY DESIRED RATE. 